LSA Safety

Industry and government officials alike have every good intention of ensuring that light-sport flying offers at least an equivalent level of safety to what we've grown accustomed to throughout the rest of general aviation.

There haven't been enough LSA accidents to provide adequate data for the kind of analysis that can be done for the rest of the general aviation fleet. On an anecdotal basis, however, light-sport accidents already show some elements that are common to the rest of general aviation accidents. These include running out of gas, improper in-flight decisions by the pilot and failure to maintain airspeed, which results in a stall.

In one major respect, an LSA should be safer to fly than the stock general aviation aircraft to which we've been accustomed. Under the FAA's classification, an LSA can have a maximum takeoff weight of only 1,320 pounds (1,430 for seaplanes), a maximum stall speed of 51 mph (41 knots) and a maximum speed in level flight with continuous maximum power of 138 mph (120 knots). Less speed and less weight should translate into less energy that needs to be dissipated in an accident sequence and more room for the pilot to engineer a controlled crash situation. As we all know, you're more likely to survive when the airplane is kept under control.

It's a bit too early in the game to determine the extent to which LSAs may replace larger general aviation planes as real transportation machines. Some of the LSAs in the marketplace have the capability to be reasonably dependable for getting from point A to point B at a good speed and with excellent fuel efficiency, provided the weather cooperates. Many of the LSA accidents investigated so far have occurred during local flights. It will take time to determine whether there's any correlation between LSA accidents and distances flown, and the roles played by elements such as en route decision making, pilot fatigue and navigation.

Safety has been at the forefront for LSA manufacturers, as well as the FAA and pilot "alphabet" organizations. One manufacturer, for example, has its own training-transition syllabus to supplement FAA-required training. It's designed to help ensure that new students and already-licensed pilots are brought up to speed on differences between LSAs and others before being turned loose. A recurring theme is that existing pilots need to understand that while LSAs may look similar to what we're used to, there are differences. The manufacturer notes that lighter weight and low wing loading may make an LSA more sensitive to wind and turbulence. Landing-gear feel and shock-absorbing capability may be markedly different from other aircraft pilots have flown. The large unobstructed canopy and different seat position may require an adjustment of the viewing angles to which pilots have become accustomed. The sound of a higher-revving engine may take some getting used to. Even cleaning and maintaining the appearance of the nonaluminum materials used in LSA construction involves new learning.

Here are some examples of LSA accidents recently investigated by the NTSB.

On March 10, 2007, a Flight Design CT-SW was being used by a company's chief pilot, who held an ATP rating, and an instructor who was undergoing training at the Double Eagle II Airport in Albuquerque, N.M. The student instructor had performed four touch-and-go landings to runway 22, which is 7,400 feet by 100 feet. On the fifth landing, the aircraft's approach speed was normal and the wind was calm. The student instructor started the flare when the aircraft was two to three feet above the runway. As the airplane settled, the chief pilot raised the nose slightly to prevent what he thought might be a bounced landing. The airplane then ballooned up, and the pilots decided to execute a go-around. The chief pilot added power and eased the nose up some more. Instead of gaining altitude, the airplane settled to the runway in a slight left crab. It touched down first on the left main landing gear, which broke. The airplane then slid along the runway for about 300 feet, went off the runway's left side and flipped over.

Examination revealed that the left main lower landing-gear tube had fractured due to overstress. According to the NTSB, this was consistent with a hard landing. The airplane had been operated 25 hours at the time of the accident. The NTSB determined that the probable cause of the accident was an overloading of the aircraft during landing leading to the total failure of the left main gear strut, which resulted in loss of control and subsequent nose-over. A factor contributing to the accident was the chief pilot's inability to maintain directional control of the airplane after the landing gear failed.

On April 2, 2006, a CZAW Parrot was taking off from runway 09, a 1,980-foot-long turf runway at Palm City, Fla. The weather was good with no ceiling, visibility 10 miles, and wind from 130 degrees at seven knots. During the takeoff roll, the engine was only able to develop 4,300 rpm. (Full power is 5,500 rpm.)The airplane lifted off and made it over the tops of some trees. However, the rate of climb decreased, and the pilot didn't think the airplane would make it over additional obstructions ahead. So, he maneuvered back to the airstrip. During a hard landing, the right main landing gear broke off and the 5,000-hour commercial pilot received serious injuries. Examination of the engine revealed that the throttle cables were bent.

The NTSB determined that the probable cause of this accident was failure of the pilot to abort the takeoff after recognizing that the engine was not developing full power during the takeoff roll. A contributing factor was the bending of the throttle cables which prevented full movement of the throttle control.

On November 11, 2006, a private pilot was flying a CZAW Zenith Air in the area around Basye, Va., on November 11, 2006. It was a good VFR day, with no ceiling, visibility 10 miles, and the wind from 180 degrees at five knots. When the airplane was about one mile northeast of the airport, the engine surged and then quit. The airplane subsequently descended into trees in a residential area. The pilot, who was the only occupant, was killed.

Examination of the wreckage revealed only traces of fuel in the tanks and fuel system. There was no evidence that the propeller was rotating at impact. Investigators determined that the accident flight was the airplane's seventh since it was last refueled. Total operating time since the refueling was about 6.3 hours. The airplane could carry 30 gallons, and the Rotax 912 ULS engine burned a high of 7.1 gph at takeoff performance and about 4 gph at maximum cruise power. The Airplane Flight Manual advises to "visually confirm fuel level" during preflight and to "check fuel quantity" before takeoff.

The NTSB determined that the probable cause of this accident was the pilot's inadequate preflight inspection, which resulted in a total loss of engine power due to fuel exhaustion.

On August 7, 2005, an Allegro 2000 was being used for a dual instructional flight in the area around Oak Island, N.C. Visual meteorological conditions prevailed, with no ceiling, visibility of 10 miles and the wind from 100 degrees at six knots. When the airplane failed to return to the airport as scheduled, a search was initiated. The airplane was found to have crashed in an open field. Both the flight instructor and student had been killed.

Investigators noted that damage to the airframe was consistent with a low-energy impact after an uncontrolled descent, leading them to find that the airplane was in a stall as it descended. The flaps were found extended to 15 degrees. According to literature from the manufacturer, the airplane's stall speed with 15 degrees of flaps and the engine at idle power is 48 mph. During a test run of the engine, no preimpact mechanical problems were identified. The engine ran at full power. The only discrepancy noted was that an FAA inspector had approved issuance of the airworthiness certificate for the aircraft to operate in the S-LSA (special LSA) category without ensuring that the Pilot Operating Handbook contained all required information. Missing from the documentation was information on fuel capacity, service ceiling, best angle and rate of climb, and a few other items. But, the Safety Board said this had nothing to do with the accident.

The NTSB determined that the probable cause of the accident was the instructor's failure to maintain airspeed for unknown reasons, resulting in an aerodynamic stall and subsequent collision with the ground.

Peter Katz is editor and publisher of NTSB Reporter, an independent monthly update on aircraft accident investigations and other news concerning the National Transportation Safety Board. To subscribe, write to: NTSB Reporter, Subscription Dept., P.O. Box 831, White Plains, NY 10602-0831.